Wyniki wyszukiwania - Biblioteka Nauki

1

Effects of sowing date on yield, gas exchange, chlorophyll fluorescence, membrane termo-stability, carbohydrates and protein content of durum and bread wheat cultivars

100%

Bagheri A.

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tom 545

EN

In this study two sowing date in years 2007-08 (1 November as normal sowing date and 1 January as late sowing date) were used. Measurements of chlorophyll fluorescence, membrane thermo-stability, gas exchange parameters and carbohydrates content in two wheat cultivars (Dena as durum wheat and Roshan as bread wheat) at post- anthesis stage were recorded. Acquired thermo-tolerance showed significant variation in late sown conditions. It was inferred that durum wheat conferred less relative injury and greater thermo-tolerance possibly through maintaining cellular membrane integrity under high temperature stress. Data based on chlorophyll fluorescence revealed a reduction of mean value of both cultivars for Fv/Fm, in late sown conditions. There were not any significant differences in all measured traits between two experimental years. Heat stress, occurred in late sown condition, caused reduction in biological and grain yield, harvest index, number of seed per ear, ear length and grain weight of two cultivars. But these reductions in durum wheat were lower. Seed protein content of cultivars increased in late sowing date. There were significant differences between cultivars in protein content. The grain yield reduction in cv. Roshan was higher than Dena. It seemed that by increasing in fructan and glucose content, rather than starch content, durum wheat can cope on the heat stress better than bread wheat.

PL

W badaniach w latach 2007-2008 wybrano dwa terminy siewu (1 listopad jako termin siewu normalny oraz 1 styczeń jako termin późny). Wykonano pomiary, fluorescencji chlorofilu, termostabilności membran, parametrów wymiany gazowej i zawartości węglowodanów u dwóch odmian pszenicy (Dena - pszenica twarda i Roshan - pszenica zwyczajna) w fazie po kwitnieniu. Wyniki pomiarów termotoleracji wykazywały istotną zmienność w warunkach późnego siewu, co może wskazywać, że liście pszenicy twardej są mniej uszkadzane i mają wyższą termotolerancję poprzez utrzymywanie integralności membran komórkowych w warunkach stresu wysokiej temperatury. Wyniki pomiarów fluorescencji chlorofilu wykazały u obu odmian obniżenie średniej wartości Fv/Fm, w warunkach późnego siewu. Nie stwierdzono istotnych różnic w wartościach mierzonych cech w obu latach doświadczenia. Stres temperaturowy, pojawiający się w warunkach późnego terminu siewu o obu badanych odmian, powodował obniżenie plonu biologicznego, plonu ziarna, wskaźnika plonowania, liczby nasion w kłosie, długości kłosa oraz masy ziarna. Obniżenie tych wartości było mniejsze u pszenicy twardej. Zawartość białka w nasionach wzrosła u odmian wysianych później. Stwierdzono istotne różnice pomiędzy odmianami w zawartości białka. Obniżenie plonu u odmiany Roshan było wyższe niż u odmiany Dena. Można przypuszczać, że pszenica twarda lepiej radzi sobie ze stresem temperaturowym niż pszenica zwyczajna, bardziej przez zwiększenie zawartości fruktanów i glukozy niż zawartość skrobi.

2

Thermodynamic Phase Diagram and Phonon stability, Electronic and Optical Properties of FeVSb: A DFT study

51%

Bagheri A. , Boochani A. , Masharian S. R. , Jafarpour F. H.

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tom Vol. 68, iss. 1

331--338

EN

Mechanical, electronic, thermodynamic phase diagram and optical properties of the FeVSb half-Heusler have been studied based on the density functional theory (DFT) framework. Studies have shown that this structure in the MgAgAs-type phase has static and dynamic mechanical stability with high thermodynamic phase consistency. Electronic calculations showed that this compound is a p-type semiconductor with an indirect energy gap of 0.39 eV. This compound’s optical response occurs in the infrared, visible regions, and at higher energies its dielectric sign is negative. The Plasmon oscillations have occurred in 20 eV, and its refraction index shifts to zero in 18 eV.

3

Determination of kinematic parameters of a passive bipedal walking robot moving on a declined surface by image processing

45%

Bagheri A. , Alitavoli M. , Hajiloo A. , Basiri S. , Asadi H.

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2006

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tom Vol. 16, nr 1-2

94--100

EN

Purpose: This paper describes the design and manufacturing of the mechanisms that are able to move on a slope according to its gravity. Design/methodology/approach: After presenting the governing equations and the dynamics of the robot, a computer simulation is developed. A comparison between the results from the physical model and the results from the numerical simulation is done to check the validity of the project. Findings: This robot is able to move down on slope with a minimum tangent based on the gravity and without any controller or any supplier. Research limitations/implications: Image processing has blind nodes in some frames and can not determine node positions and at this paper a method for getting rid of that problem has been developed. Position accuracy depends on ability of processing unit. Practical implications: This method could be used for finding of kinematic parameters of each manipulator while moving. Originality/value: This paper describes a method for finding kinematic parameters of a passive robot by image processing.

4

Drought stress effects on photosynthesis, chlorophyll fluorescence and water relations in tolerant and susceptible chickpea (Cicer arietinum L.) genotypes

45%

Rahbarian R. , Khavari-Nejad R. , Ganjeali A. , Bagheri A. , Najafi F.

Acta Biologica Cracoviensia. Series Botanica

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2011

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tom 53

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nr 1

EN

In order to evaluate morphological and physiological traits related to drought tolerance and to determine the best criteria for screening and identification of drought-tolerant genotypes, we grew two tolerant genotypes (MCC392, MCC877) and two sensitive genotypes (MCC68, MCC448) of chickpea under drought stress (25% field capacity) and control (100% field capacity) conditions and assessed the effect of drought stress on growth, water relations, photosynthesis, chlorophyll fluorescence and chlorophyll content in the seedling, early flowering and podding stages. Drought stress significantly decreased shoot dry weight, CO2 assimilation rate (A), transpiration rate (E), and PSII photochemical efficiency (Fv/Fm) in all genotypes. In the seedling and podding stages, PSII photochemical efficiency was higher in tolerant genotypes than in sensitive genotypes under drought stress. Water use efficiency (WUE) and CO2 assimilation rate were also higher in tolerant than in sensitive genotypes in all investigated stages under drought stress. Our results indicated that water use efficiency, A and Fv/Fm can be useful markers in studies of tolerance to drought stress and in screening adapted cultivars of chickpea under drought stress.